The rapid determination  of alumina in opal glass*

GT V02 1961 071-073

To facilitate analytical control of glass composition, a rapid method for alumina in opal glass has been devised. After decomposition of the glass sample with hydro-fluoric and perchloric acids, aluminium, zinc, etc., are complexed with ethylendiaminetera-acetic acid (ED T A) and the excess of this reagent is removed by titration with zinc solution. Sodium fluoride is then added to displace EDTA from its complex with aluminium and the determination is completed by titration of the liberated E DT A with standard zinc solution. The method is capable of high precision; results on a sample of opal glass containing 4% of alumina had a standard deviation of 0.01% A1203. After a crushed sample of glass has been prepared duplicate determinations can be completed in 14 to 2 hours